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| 2. |
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| 3. |
- Chen, Yang, et al.
(författare)
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Crystal structure of linoleate 13R-manganese lipoxygenase in complex with an adhesion protein.
- 2016
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Ingår i: Journal of Lipid Research. - 0022-2275 .- 1539-7262. ; 57:8, s. 1574-1588
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Tidskriftsartikel (refereegranskat)abstract
- The crystal structure of 13R-manganese lipoxygenase (MnLOX) of Gaeumannomyces graminis (Gg) in complex with zonadhesin of Pichia pastoris was solved by molecular replacement. Zonadhesin contains β-strands in two subdomains. A comparison of Gg-MnLOX with the 9S-MnLOX of Magnaporthe oryzae (Mo) shows that the protein fold and the geometry of the metal ligands are conserved. The U-shaped active sites differ mainly due to hydrophobic residues of the substrate channel. The volumes and two hydrophobic side pockets near the catalytic base may sanction oxygenation at C-13 and C-9, respectively. Gly-332 of Gg-MnLOX is positioned in the substrate channel between the entrance and the metal center. Replacements with larger residues could restrict oxygen and substrate to reach the active site. C18 fatty acids are likely positioned with C-11 between Mn(2+)OH2 and Leu-336 for hydrogen abstraction and with one side of the 12Z double bond shielded by Phe-337 to prevent antarafacial oxygenation at C-13 and C-11. Phe-347 is positioned at the end of the substrate channel and replacement with smaller residues can position C18 fatty acids for oxygenation at C-9. Gg-MnLOX does not catalyze the sequential lipoxygenation of n-3 fatty acids in contrast to Mo-MnLOX, which illustrates the different configurations of their substrate channels.
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| 4. |
- Hammarström, Lars G. J., et al.
(författare)
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The Oncolytic Efficacy and in Vivo Pharmacokinetics of [2-(4-Chlorophenyl)quinolin-4-yl](piperidine-2-yl)methanol (Vacquinol-1) Are Governed by Distinct Stereochemical Features
- 2016
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Ingår i: Journal of Medicinal Chemistry. - : American Chemical Society (ACS). - 0022-2623 .- 1520-4804. ; 59:18, s. 8577-8592
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Tidskriftsartikel (refereegranskat)abstract
- Glioblastoma remains an incurable brain cancer. Drugs developed in the past 20 years have not improved the prognosis for patients, necessitating the development of new treatments. We have previously reported the therapeutic potential of the quinoline methanol Vacquinol-1 (1) that targets glioblastoma cells and induces cell death by catastrophic vacuolization. Compound 1 is a mixture of four stereoisomers due to the two adjacent stereogenic centers in the molecule, complicating further development in the preclinical setting. This work describes the isolation and characterization of the individual isomers of 1 and shows that these display stereospecific pharmacokinetic and pharmacodynamic features. In addition, we present a stereoselective synthesis of the active isomers, providing a basis for further development of this compound series into a novel experimental therapeutic for glioblastoma.
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| 5. |
- Oliw, Ernst H, et al.
(författare)
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Chiral phase-HPLC separation of hydroperoxyoctadecenoic acids and their biosynthesis by fatty acid dioxygenases.
- 2015
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Ingår i: Methods in Molecular Biology. - New York, NY : Springer New York. - 1064-3745 .- 1940-6029. ; 1208, s. 85-95
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Tidskriftsartikel (refereegranskat)abstract
- Fatty acid oxygenases are often characterized by steric analysis of their hydroxy or hydroperoxy metabolites. Chiral phase-HPLC (CP-HPLC) can be used to separate enantiomeric hydroperoxyoctadecenoic acids. This method is based on analysis of seven octadecenoic fatty acids with double bonds at positions 6Z to 13Z, which were oxidized to hydroperoxides by photooxidation. A stationary phase, Reprosil Chiral NR, was found to resolve these hydroperoxy fatty acids with 1-hydroperoxy-2-propene and with 3-hydroperoxy-1-propene elements so that the S hydroperoxy fatty acids consistently eluted before the R stereoisomers. The chiral selector has not been disclosed, but it is described as an aromatic chiral phase with π-donor and π-acceptor groups of Pirkle type. The MS(3) spectra of the hydroperoxides showed characteristic fragments, which were influenced by the distance between the hydroperoxy and the carboxyl groups and the relative position of the double bond. Octadecenoic fatty acids can be oxidized by fungal and bacterial dioxygenases to hydroperoxides with cis or trans double bond configuration. Steric analysis of the hydroperoxy metabolites can be performed by this method, and it can also be used for preparative purposes.
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| 6. |
- Oliw, Ernst H., et al.
(författare)
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Stereoselective oxidation of regioisomeric octadecenoic acids by fatty acid dioxygenases
- 2011
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Ingår i: Journal of Lipid Research. - 0022-2275 .- 1539-7262. ; 52:11, s. 1995-2004
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Tidskriftsartikel (refereegranskat)abstract
- Seven Z-octadecenoic acids having the double bond located in positions 6Z to 13Z were photooxidized. The resulting hydroperoxy-E-octadecenoic acids [HpOME(E)] were resolved by chiral phase-HPLC-MS, and the absolute configurations of the enantiomers were determined by gas chromatographic analysis of diastereoisomeric derivatives. The MS/MS/MS spectra showed characteristic fragments, which were influenced by the distance between the hydroperoxide and carboxyl groups. These fatty acids were then investigated as substrates of cyclooxygenase-1 (COX-1), manganese lipoxygenase (MnLOX), and the (8R)-dioxygenase (8R-DOX) activities of two linoleate diol synthases (LDS) and 10R-DOX. COX-1 and MnLOX abstracted hydrogen at C-11 of (12Z)-18:1 and C-12 of (13Z)-18:1. (11Z)-18:1 was subject to hydrogen abstraction at C-10 by MnLOX and at both allylic positions by COX-1. Both allylic hydrogens of (8Z)-18:1 were also abstracted by 8R-DOX activities of LDS and 10R-DOX, but only the allylic hydrogens close to the carboxyl groups of (11Z)-18:1 and (12Z)-18:1. 8R-DOX also oxidized monoenoic C(14)-C(20) fatty acids with double bonds at the (9Z) position, suggesting that the length of the omega end has little influence on positioning for oxygenation. We conclude that COX-1 and MnLOX can readily abstract allylic hydrogens of octadecenoic fatty acids from C-10 to C-12 and 8R-DOX from C-7 and C-12.
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| 7. |
- Sooman, Linda, et al.
(författare)
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Replacement of two amino acids of 9R-dioxygenase-allene oxide synthase of Aspergillus niger inverts the chirality of the hydroperoxide and the allene oxide
- 2016
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Ingår i: Biochimica et Biophysica Acta. - : Elsevier BV. - 0006-3002 .- 1878-2434. ; 1861:2, s. 108-118
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Tidskriftsartikel (refereegranskat)abstract
- The genome of Aspergillus niger codes for a fusion protein (EHA25900), which can be aligned with ~50% sequence identity to 9S-dioxygenase (DOX)-allene oxide synthase (AOS) of Fusarium oxysporum, homologues of the Fusarium and Colletotrichum complexes and with over 62% sequence identity to homologues of Aspergilli, including (DOX)-9R-AOS of Aspergillus terreus. The aims were to characterize the enzymatic activities of EHA25900 and to identify crucial amino acids for the stereospecificity. Recombinant EHA25900 oxidized 18:2n-6 sequentially to 9R-hydroperoxy-10(E),12(Z)-octadecadienoic acid (9R-HPODE) and to a 9R(10)-allene oxide. 9S- and 9R-DOX-AOS catalyze abstraction of the pro-R hydrogen at C-11, but the direction of oxygen insertion differs. A comparison between twelve 9-DOX domains of 9S- and 9R-DOX-AOS revealed conserved amino acid differences, which could contribute to the chirality of products. The Gly616Ile replacement of 9R-DOX-AOS (A. niger) increased the biosynthesis of 9S-HPODE and the 9S(10)-allene oxide, whereas the Phe627Leu replacement led to biosynthesis of 9S-HPODE and the 9S(10)-allene oxide as main products. The double mutant (Gly616Ile, Phe627Leu) formed over 90% of the 9S stereoisomer of HPODE. 9S-HPODE was formed by antarafacial hydrogen abstraction and oxygen insertion, i.e., the original H-abstraction was retained but the product chirality was altered. We conclude that 9R-DOX-AOS can be altered to 9S-DOX-AOS by replacement of two amino acids (Gly616Ile, Phe627Leu) in the DOX domain.
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| 8. |
- Wallin, Jeanette, et al.
(författare)
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Discrepancy in responses to the surprise question between hemodialysis nurses and physicians, with focus on patient clinical characteristics : A comparative study
- 2023
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Ingår i: Hemodialysis International. - : John Wiley & Sons. - 1492-7535 .- 1542-4758. ; 27:4, s. 454-464
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Tidskriftsartikel (refereegranskat)abstract
- Introduction: The surprise question (SQ) "Would I be surprised if this patient died within the next xx months" can be used by different professions to foresee the need of serious illness conversations in patients approaching end of life. However, little is known about the different perspectives of nurses and physicians in responses to the SQ and factors influencing their appraisals. The aim was to explore nurses' and physicians' responses to the SQ regarding patients on hemodialysis, and to investigate how these answers were associated with patient clinical characteristics. Methods: This comparative cross-sectional study included 361 patients for whom 112 nurses and 15 physicians responded to the SQ regarding 6 and 12 months. Patient characteristics, performance status, and comorbidities were obtained. Cohen's kappa was used to analyze the interrater agreement between nurses and physicians in their responses to the SQ and multivariable logistic regression was applied to reveal the independent association to patient clinical characteristics. Findings: Proportions of nurses and physicians responding to the SQ with "no, not surprised" was similar regarding 6 and 12 months. However, there was a substantial difference concerning which specific patient the nurses and physicians responded "no, not surprised", within 6 (kappa = 0.366, p < 0.001, 95% CI = 0.288-0.474) and 12 months (kappa = 0.379, p < 0.001, 95% CI = 0.281-0.477). There were also differences in the patient clinical characteristics associated with nurses' and physicians' responses to the SQ. Discussion: Nurses and physicians have different perspectives in their appraisal when responding to the SQ for patients on hemodialysis. This may reinforce the need for communication and discussion between nurses and physicians to identify the need of serious illness conversations in patients approaching the end of life, in order to adapt hemodialysis care to patient preferences and needs.
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| 10. |
- Wennman, Anneli, 1984-, et al.
(författare)
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Catalytic convergence of manganese and iron lipoxygenases by replacement of a single amino Acid
- 2012
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Ingår i: Journal of Biological Chemistry. - 0021-9258 .- 1083-351X. ; 287:38, s. 31757-31765
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Tidskriftsartikel (refereegranskat)abstract
- Lipoxygenases (LOXs) contain a hydrophobic substrate channel with the conserved Gly/Ala determinant of regio- and stereospecificity and a conserved Leu residue near the catalytic non-heme iron. Our goal was to study the importance of this region (Gly(332), Leu(336), and Phe(337)) of a lipoxygenase with catalytic manganese (13R-MnLOX). Recombinant 13R-MnLOX oxidizes 18:2n-6 and 18:3n-3 to 13R-, 11(S or R)-, and 9S-hydroperoxy metabolites (∼80-85, 15-20, and 2-3%, respectively) by suprafacial hydrogen abstraction and oxygenation. Replacement of Phe(337) with Ile changed the stereochemistry of the 13-hydroperoxy metabolites of 18:2n-6 and 18:3n-3 (from ∼100% R to 69-74% S) with little effect on regiospecificity. The abstraction of the pro-S hydrogen of 18:2n-6 was retained, suggesting antarafacial hydrogen abstraction and oxygenation. Replacement of Leu(336) with smaller hydrophobic residues (Val, Ala, and Gly) shifted the oxygenation from C-13 toward C-9 with formation of 9S- and 9R-hydroperoxy metabolites of 18:2n-6 and 18:3n-3. Replacement of Gly(332) and Leu(336) with larger hydrophobic residues (G332A and L336F) selectively augmented dehydration of 13R-hydroperoxyoctadeca-9Z,11E,15Z-trienoic acid and increased the oxidation at C-13 of 18:1n-6. We conclude that hydrophobic replacements of Leu(336) can modify the hydroperoxide configurations at C-9 with little effect on the R configuration at C-13 of the 18:2n-6 and 18:3n-3 metabolites. Replacement of Phe(337) with Ile changed the stereospecific oxidation of 18:2n-6 and 18:3n-3 with formation of 13S-hydroperoxides by hydrogen abstraction and oxygenation in analogy with soybean LOX-1.
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